Suzanne Slacas, left, and Terry Gist with the South Carolina Education Lottery hang a banner at the KC Mart in Simpsonville, where lottery officials said someone in South Carolina won the record $1.6 billion Mega Millions jackpot. Anna B. Mitchell/The Greenville News

COLUMBIA — Last October, someone in South Carolina became a billionaire overnight. And it’s possible they don’t even know it.

Here is what we do know. The winning lottery ticket with all six matching numbers — for a $1.5 billion Mega Millions jackpot drawing on Oct. 23 — was purchased by someone at a gas station outside Simpsonville.

What happened next could be South Carolina’s biggest mystery of 2018.

This mysterious individual — or, maybe, it’s a group of mysterious individuals — has 180 days to claim their winnings. But, as of this week, no one has come forward to claim the billion-dollar prize, and time slowly is running out.

“This is unusual, considering that it’s $1.5 billion,” said Holli Armstrong with the S.C. Lottery Commission, still waiting on someone to come forward with the winning ticket.

If the money isn’t claimed by late April, the $1.5 billion will return to the 44 states that hold Mega Millions lotteries. South Carolina’s total from that pot would add up to $11.2 million, which would go into the state’s education fund.

But that would be a step down in how much money the state could collect from a winner coming forward. Tony Cooper, chief operating officer of the S.C. Education Lottery, estimated South Carolina would collect about $70 million in state taxes as part of a payout.

So why has the winner not yet come forward, two months after the big drawing?

It may be the winner no longer is in South Carolina.

Simpsonville is close to two major interstates, I-185 and I-385 south of Greenville. A driver from out of state may have stopped off at the KC Mart No. 7, bought a ticket and kept driving out of the Palmetto State.

But the gas station is about 5 miles from the closest interstate exit, on the other side of town in a residential area.

And, even if the winning ticket was bought by an out-of-state visitor, a S.C.-sold ticket still would have to be redeemed with the S.C. Lottery Commission.

Why the delay?

Tax experts say the winner may want to get his or her financial situation in order before they take on more money than many people ever will see in their lives.

“This can be a life-changing amount of money,” said Ken Newhouse, an accountant with West Columbia’s Moore Beauston & Woodham firm and legislative liaison for the S.C. Association of CPAs.

“But a lot of people don’t know how to control it, and they lose it over time,” Newhouse warns.

The S.C. Lottery advises winners to speak to a professional tax adviser and an attorney before they collect their winnings. That is because the winner may need more specialized financial services than someone who only has dealt with a checking account.

Joe Poore, a senior manager with the Elliott Davis accounting firm in Greenville, thinks the winner may see a tax advantage in waiting to claim the money until after Jan. 1.

Since the passage of a new tax overhaul in 2017, there have not been major changes to tax laws. But when the winner receives the payout will determine the year when tax has to be paid — next April 15 for winnings claimed this year — versus a full year later — in April 2020 — for income received in January.

“That’s 16 more months it can sit in a bank and collect interest,” Poore said. “That could be a difference of millions of dollars.”

If the winner accepts one lump-sum payment, around a quarter of the winnings will be withheld for taxes, leaving the winner with $878 million. But more of that income still would be taxable on the next April 15. Delaying the payout would allow the winner to defer paying taxes on more than $100 million until 2020.

The winner also has the option of taking an annuity of $1.5 billion in 30 payments.

The downside to sudden wealth

Newhouse says the winner could set up a trust or a charitable foundation. That would protect more of the money from the tax man, and it also would give the winner a vehicle to spend their money in a more philanthropic way.

“We’ve had other winners who have done a lot of good,” he said.

In the Columbia area, retired state employee Solomon Jackson won a $260 million Powerball jackpot in 2009. Afterward, Jackson gave money to several good causes, mainly educational — including $10 million to Morris College in Sumter, $1.7 million to the University of South Carolina and $1.25 million to Midlands Technical College.

Jackson also gave $1 million to the S.C. State Museum, spent $500,000 to buy two new luxury coaches for Columbia’s Benedict College and $2 million to preserve the historic auditorium at the former Booker T. Washington High School in Columbia.

But there is a downside to sudden wealth.

Jackson’s generosity has made him a target for those seeking a contribution for one cause or another, said attorney I.S. Leevy Johnson, a friend.

“You’re going to get requests coming in from all around the world,” Johnson warns the billion-dollar lottery winner. “And the majority of them are not good causes. It’s ‘My golf course is going bankrupt. My development is going bankrupt.’ ”

That’s why a financial adviser is important.

Poore of Elliott Davis recommends the winner to decide ahead of time how much of the money they want to give away and to what causes.

“You can say 20 percent will be given away over this time horizon, and these are the three kinds of charities I want to give to,” Poore said. “Then, if you get a request that doesn’t fit in that bucket, it’s not such an emotional decision. You just say, ‘I’m sorry. This doesn’t align with my goals.’ ”

Does the winner even know?

But there the mystery deepens again.

S.C. financial experts say they haven’t heard of anyone — such as an unknown, anonymous lottery winner — looking to line up tax attorneys or create special financial vehicles.

“You would see something,” Poore said. “Especially given how hard it is to remain anonymous. When everybody is looking for the golden ticket, anything you do is going to be picked up.”

South Carolina does allow lottery winners to remain anonymous. But it is hard for someone not to be obvious when they come into money and, suddenly, buy a big BMW, for instance, or upgrade to a more fancy vacation spot.

The absence of any visible activity by the lottery winner raises a question: Does the winner even know they won $1.5 billion? Do they even still have the ticket?

Poore thinks anxiety might be playing a role in the prize winner’s delay in coming forward. Even after buying a ticket, the winner may not be ready for just how much their life is about to change.

But if the winner does overcome their worries or gets their foundation set up — or reads this story and starts looking through the pants pockets in their closet — tickets can be presented at the lottery’s claims center on Assembly Street, Mondays through Fridays, from 8:30 a.m. to 5 p.m.